Oscillator and frequency changer



Aug. 1, 1939. DE vR|Es AL 2,168,295

OSCILLATOR AND FREQUENCY CHANGER Filed April 15, 1937 2 Sheets-Sheet 1 ENVELOPE MAGNET/C FIELD COIL I E TOR GERAIT DE mlEs AND NV N 5 BY CA/RZA. (UNDER/V v ATTORNEY Aug} 1, 1939- 6. DE VRIES ET AL 2,168,295

OSCILLATOR AND FREQUENCY CHANGER Filed April 15, 1937 2 Sheets-Sheet 2 MAGNET/6' F/ELD co/L INVENTORS GERR/T DE VRIES mvn CAR GA. 14 LINDERN c/Rcu/r FOR osp/mr/ou 0F 7 7 THIRD-SUB'HARMON/C ATTORNEY Patented Aug. 1, 1939 OSCILLATOR AND FREQUENCY CHANGER Gerrit de Vries and Carl G. A. von Lindern,

Eindhoven, Netherlands,

Philips Netherlands Gloeilampenfabrieken,

assignors to N. V. Eindhoven,

Application April 15, 1937, Serial No. 137,04 In the Netherlands June 5, 1936 13 Claims.

This invention has reference to oscillators and circuits for multiplying or dividing the frequency of high-frequency or ultra-high-frequency oscillations. The device disclosed includes a magnetron comprising more than two anodes which are arranged along the circumference of a cylindrical surface, said anodes being divided into two groups and all the anodes of one group being connected to all the anodes of the other group via an oscillatory circuit and at least two anodes of the same group being interconnected via a circuit tuned to a harmonic or sub-harmonic of the frequency to which the first mentioned circuit is tuned.

In one form of construction of our novel circuit arrangement the anodes of each group are separated from the anodes of the other group by a surface of symmetry passing through the axis of the cylindrical surface formed by the anodes.

In a different embodiment each anode pertains to a group other than that of the adjacent anodes.

In order that the invention may be clearly understood and readily carried into effect some few embodiments thereof will now be described more fully with reference to the accompanying drawings, in which:

Figure 1 shows a magnetron circuit arrangement in which the magnetron tube comprises two pairs of anode segments;

Fig. 2 shows a modification in which the magnetron comprises two anode segments of one group and a single anode segment in a second group;

Fig. 3 shows a circuit arrangement suitable for producing a third harmonic'of the fundamental frequency;

Fig. 4 shows a modification of the arrangement of Fig. 3;

Fig. 5 shows an embodiment of the invention in which the magnetron tube comprises four anodes of one group and a single anode of a second group;

Fig. 6 shows a modification in which the magnetron comprises two anodes in one group and three anodes in a second group;

wise shown in Fig. 8 but having a total of six anode segments Within the magnetron.

The circuit shown in Fig. 1 includes a magnetron having two pairs of anodes. The cathode 3 is shown normal to the surface of the drawings. The magnetron comprises four anodes 2, 4, 6 and 8 which are arranged along the circumference of a cylindrical surface. The anodes of the tube l are divided into two groups separated from each other by a surface which passes through the axis of the cylindrical surface formed by the anodes and which is'shown in dotted lines. Thus, the anodes 2 and 4 pertain to one group and the anodes 6 and 8 to the other group. The anodes 2 and 4 of the first group are interconnected through a circuit 5 tuned to the second harmonic of the frequency to be amplified. The anodes 6 and 8 of the other group are interconnected via an oscillatory circuit 1 tuned to the same frequency as the circuit 5. The middle points of the circuits 5 and l are interconnected through an impedance which jointly with the circuits 5 and lconstitutes the circuit 9 which is tuned to the frequency to be multiplied. The middle point of the circuit 9 is connected to the positive terminal of a source of anode Voltage, the negative terminal of which is connected to the cathode 3. The cathode supply Voltage necessary for the cathode 3 is not shown on the drawings. 30

The principle underlying the working of the circuit described consists in that the magnetron behaves for the oscillations to be multiplied as a magnetron having only two anodes, since for the oscillations occurring in the circuit 9, the voltages occurring at the anodes 2 and 4 or 6 and 8, respectively, are the same which can be insured by a correct choice of the impedances of the circuits 5 and 1. Thus, when the oscillations to be multiplied are supplied to the circuit 9, an electric alternating field is set up between the anodes 2 and 4 on the one hand, and the anodes 6 and 8 on the other hand, and there is in addition a magnetic field. Under the influence of these two fields the electrons emitted from the cathode traverse a spiral path around the cathode, part of these electrons passing in succession past the anodes 2, 4, 6 and 8. The speed at which the said path is traversed by the electrons is such that during half the period of the oscillations occurring in the circuit 9, the electrons have traversed along the circumference of the cylindrical surface formed by the anodes a path which covers an angle of When this path is being traversed part of the electrons pass in succession stitutes the circuit 9.

past the anodes 2 and 4 or 9 and 8, respectively, so that the circuit which connects the anodes 2 and 4 or 6 and 8, respectively, is excited during half the period of the oscillations supplied to the circuit 9, once at the anode 2 or 6, respectively, and once at the anode l or 8, respectively, and the time between the excitment at the anode 2 or 6, respectively, and at the anode 4 or 8, respectively, is half the half-period of the oscillations occurring in the circuit 9. The circuits and I will, therefore, have occurring in them oscilla tions, the frequency of which is equal to twice the frequency of the oscillations to be multiplied supplied to the circuit 9.

The circuit described is suitable both for multiplying and for dividing high frequency and ultrahigh frequency oscillations. In the latter case the oscillations to be divided are supplied to the circuits 5 and 1, after which oscillations having a frequency that is half the frequency of the oscillations supplied to the circuits 5 and 1 can be derived from the circuit 9. The oscillations, the frequency of which is to be multiplied or to be divided, may also be generated by the magnetron itself.

If the oscillations supplied to the circuit 9 or set up in the circuit 9 are to be multiplied, it is not desirable that the circuit should have a tendency to generate oscillations having the frequency of the circuits 5 and I. A circuit which is relatively free from this tendency is shown in Fig. 2.

The circuit of Fig. 2 includes a magnetron in which one group consists of the anodes 2 and 4, and the other group of a single anode ID. The anodes 2 and 4 of one group are interconnected via an oscillatory circuit 5, the middle point of which is connected to the anode 19 through an impedance which jointly with the circuit 5 con- When the oscillations to be multiplied are supplied to the circuit 9, or set up in the circuit 9, it is possible to derive from the circuit 5 oscillations, the frequency of which is the second harmonic of the oscillations to be multiplied. Conversely, the circuit is suited for the division in frequency of high frequency and ultra-high frequency oscillations if the oscillations to be divided are supplied to the circuit 5. But this circuit does not permit of generating oscillations having the natural frequency of the circuit 5. A further advantage of the circuit shown in Fig. 2 consists in that the oscillations, thefrequcncy of which has been multiplied, only occur in one circuit so that but one coupling element is required for supplying the oscillations, the frequency of which has been multiplied to a load.

An embodiment of a circuit, according to the invention, permitting of obtaining the third harmonic of a basic frequency is shown in Fig. 3 of the drawings.

In this circuit use is made of a magnetron comprising three pairs of equally large anodes. As before, the. anodes of this magnetron are divided into two groups, the anodes l2, l4 and I6 pertaining to one group, and the anodes I9, 29 and 22 to the other group. In order to ensure that the magnetron behaves for a given frequency referred to hereinafter as the basic frequency as if it contained only two anodes, all the anodes of one group are connected to all the anodes of the other group via an oscillatory circuit 9 which is tuned to the basic frequency, and to which the oscillations to be multiplied of basic frequency are supplied or in which the oscillations to be multiplied are set up, In View of each group every two adjacent anodes are interconnected via a circuit tuned to the third harmonic of the round frequency to be multiplied. These circuits H, I 3, l5 and l? form part of the circuit 9 which is connected between the anodes i2, i4 and I6 on the one hand, and the anodes I8, 29 and 22 on the other hand, to which the oscillations to be multiplied are supplied or in which they are set up. That the described circuit for the generation of the third harmonic of the oscillations occurring in the circuit 9 is suitable follows from the fact that during half the period of the oscillations to be multiplied in which the electrons traverse, along the circumference of the cylindrical surface formed by the anodes, apath which covers an angle of 180, part of the electrons pass in succession past the anodes I2, 5%, i6 and I8, 29, 22, respectively. The time which lapses between the excitement in phase opposition of each of the circuits H, i3, i5 and ll is consequently a third of half the period of the oscillations to be multiplied.

A simplification of the circuit shown in Fig. 3 is illustrated in Fig. 4. This consists in that one of the groups is formed by a single anode 24 and only two adjacent anodes l9 and it of the other group are interconnected and the anode i2 is connected directly to the anode l6. This circuit has the same advantages over the circuit shown in Fi 3 as the circuit shown in Fig. 2 over that of Fig. 1. The circuit shown in Fig. 4 is consequently not suited for the generation of oscillations the frequency of which is equal to the natural frequency of the circuit IS.

The circuit shown in Fig. 5 includes a magnetron in which one group is formed by four anodes 29, 28, 39 and 32, and the other group by a single anode 34. The anodes 26 and 30 or 28 and 32, respectively, of one group are interconnected electrically inside the tube, and the anodes 26 and 39 on the other hand, and the anodes 28 and 32 on the other hand have connected between them an oscillatory circuit l9 tuned to the fourth harmonic of a basic frequency. The middle point of the circuit I9 is connected to the anode 34 through an impedance which jointly with the said circuit [9 constitutes the circuit 9 which is tuned to the said basic frequency, That the circuit I9 has set up in it oscillations having the fourth harmonic of the ground frequency follows from the fact that during half the period of the oscillations occurring in the circuit 9, the electrons pass past the four anodes 26, 28, 30, 32 so that the circuit 19 is excited twice in phase opposition, and the time between the excitement in phase opposition of the circuit [9 is a fourth of the period of the oscillations that occur in the circuit 9.

Fig. 6 shows a form of construction in which the number of anodes of one group differs from the number of anodes of the other group. One group contains two anodes 36 and 98, which are interconnected via a tuned circuit 2! which is tuned to the second harmonic of a basic frequency. The other group comprises three anodes d0, 42 and 44 of which the adjacent anodes 49 and 42 are interconnected via a tuned circuit 23 which is tuned to the third harmonic of the basic frequency, whereas the anode All is connected directly to the anode M. The middle points of the circuits. 2! and 23 are interconnected through an impedance which jointly with the said circuits constitutes the circuit 9 to which the oscillations to be multiplied of basic frequency are supplied or in which the oscillations to be multiplied are set up.

It is possible to derive from the circuits 2| and 23 oscillations, the frequency .of which is equal to the second and the third'harmonics of the oscillations that occur in the circuit 9. The circuit shown in Fig. 6 is consequently simultaneously suited for doubling and for tripling a given basic frequency. That the circuits 2| and 23 have set up in them oscillations having the said harmonic frequencies follows from the explanation given with reference to the circuits shown in Figs. 1 and 3.

In the embodimentshown in Fig. 7 use is made of a magnetron in which one group consists of two anodes 45 and 48 which are interconnected via a circuit 25 tuned to the second harmonic of a basic frequency. The other group comprises four anodes 5t, 52, 54 and 56 of which every two adjacent anodes 50 and 52 or 54 and 55 are interconnected via an oscillatory circuit 24 or 29, respectively, which is tuned to the fourth harmonic of the basic frequency.

The middle points of the circuits 2! and 29, are interconnected via an impedance 3| which jointly with the circuits 25 and 21 constitutes the circuit 29 which is tuned to the second harmonic of the basic frequency, the middle point of the circuit 3| being connected to the middle point of the circuit 25 via an impedance which together with the said circuits 25, 21 and 29, 3| constitutes a circuit 9 to which the oscillations to be multiplied of basic frequency are supplied in or in which the said oscillations are set up. That it is possible to derive from the circuits 2? and 29 oscillations, the frequency of which is equal to the fourth harmonic of the oscillations occurring in the circuit 9, follows from the fact that during half the period of the oscillations occurring in the circuit 9, the electrons in the tube pass in succession past the anodes 50, 52, 54 and 55 and excite the circuits 21 and 29. The time which lapses between the excitement in phase opposition of each of the circuits 21 and 25 is consequently a quarter of half the period of the oscillations occurring in the circuit 9. In connection with the oscillations occurring in the circuit 3!, the tube behaves as if the anode group which consists of the anodes 5B, 52, 54 and 55 only contained two anodes, since for the oscillations occurring in the circuit 3|, the voltages at the anodes 50 and 54 or 54 and 55, respectively, are caused to be the same. It is thus possible to derive from the circuit 3| oscillations, the frequency of which is the second harmonic of the basic frequency. The circuit shown in Fig. 7 is, therefore, simultaneously suited for doubling and quadrupling the frequency of the oscillations occurring in the circuit 9.

In the form of construction shown in Fig. 8 use is made of a magnetron having four anodes 62, 54, G6 and 68 which are so divided into two groups that each anode pertains to a group other than that of the adjacent anodes. Thus, the anodes 62, 65 form one group and the anodes 64 and 58 the other group. The anodes 52 and 6B are interconnected via a circuit 33 tuned to half the frequency of a basic frequency. The anodes 54 and 58 are interconnected via a circuit 35 tuned to the same frequency. The middle points of the circuits 33 and 35 are interconnected Via an impedance which jointly with the said circuits 33 and 35 constitutes the circuit 31 which is tuned to the basic frequency, and to which oscillations to be divided in frequency are supplied or in which oscillations having the said basic frequency are set up. On accurate comparison of this circuit with the circuit of Fig. 1, it is found that the circuits 33 and 35 or 31, respectively, are connected to the anodes in a manner similar to the circuit 9 or the circuits 5 and 1, respectively, in the circuit shown in Fig. 1. The difference between the two circuits resides, therefore, solely in that the circuit of Fig. 1 comprises two circuits 5 and tuned to the doubled frequency which necessitates two coupling elements for the supply of the frequency-doubled energy to a loa-d,'whereas in the circuit arrangement shown in Fig. 8, it is only the circuit 31 from which oscillations having the doubled frequency of the oscillations supplied to the circuits 33 and 35 or the oscillations set up in the circuits can be derived.

The use of a tube comprising six anodes divided into two groups in the manner shown in Fig. 9, all the anodes of one group being connected to all the anodes of the other group by a circuit tuned to the basic frequency, permits of deriving from the circuits connected between the adjacent anodes of the same group oscillations, the frequency of which is the third sub-harmonic of the said basic frequency. In a similar manner the circuit comprising a magnetron having eight anodes permits of obtaining oscillations, the frequency of which is the fourth sub-harmonic.

The field of use of the circuit arrangement, according to the invention, is of importance where there is the need for ultra-high frequency oscillations of constant frequency. Ultra-high frequency oscillations having a frequency of the order of 400 megacycles per second and higher can no longer be generated by a retroactively coupled generator, and although a magnetron generator is suitable for generating oscillations having such a high frequency, the frequency of the oscillations generated by a magnetron generator is dependent to a marked extent upon the voltages supplied to the electrodes of a magnetron, and the frequency of the oscillations generated is, therefore, variable.

In order to permit of obtaining oscillations having a constant frequency of the above-mentioned order of magnitude, use may be made of a retroactively coupled generator which is arranged for the generation of a sub-harmonic of the desired frequency, and the generated oscillations of which are supplied to a frequency r multiplier, according to the invention.

We claim:

1. In a frequency changer, a magnetron discharge tube oscillator having a central cathode and a plurality of at least three cylindrically segmented anodes arranged in two systems, a circuit tuned to, the fundamental frequency of said oscillator and forming an interconnection between one anode system and the anodes of the other system, and means including at least one resonant loop forming an interconnection between tWo anodes of the same system for developing oscillations at a frequency harmonically related to said fundamental frequency.

2. In a frequency changer, a magnetron discharge tube oscillator having a central cathode and a plurality of at least three cylindrically segmented anodes arranged in two systems, a circuit tuned to the fundamental frequency of said oscillater and forming an interconnection between two anodes of the same system, and means including a second circuit connecting all the anodes of one system with the full complement of anodes of the other system for developing oscillations at a frequency harmonically related to said fundamental frequency.

3. In a frequency changer, a magnetron discharge tube oscillator having a central linear cathode and a plurality of surrounding segmented anodes, said anodes being grouped on the 'two sides of a bisecting plane in which said cathode lies, a resonant loop interconnecting two adjacent anodes of the same group, similar resonant loops interconnecting other adjacent anodes within a single group, all said loops being tuned to a common frequency, and a resonant loop system forming an interconnection between the loop system of one group and the loop system of the other group, the last said resonant loop system being tuned to a frequency harmonically related to the first said frequency.

4. In a frequency changer, a magnetron discharge tube oscillator having a central linear cathode and a plurality of surrounding segmented anodes, said anodes being grouped on the two sides of a bisecting plane in which said cathode lies, a resonant loop interconnecting two adjacent anodes of the same group, similar resonant loops interconnecting other adjacent anodes within a single group, the loop of one group being tuned to a given harmonic of a fundamental frequency and the loop system of the other group being tuned to another harmonic of said fundamental frequency, and a resonant loop system forming an interconnection between the respective loop systems of the two groups, the last said resonant system being tuned to said fundamental frequency.

5. In a frequency changer, a magnetron discharge tube having a central linear cathode and plurality of at least three surrounding segmented anodes, one only of said anodes being disposed on one side of a bisecting plane in which the cathode lies, a conductor interconnecting the plurality of anodes on the other side of said bisecting plane, means including a resonant loop system for determining the fundamental fre quency of oscillations in said tube, said loop system being conductively connected from the first said anode to said interconnecting conductor, and means characterizing said interconnecting conductor as another resonant loop system for developing a frequency harmonically related to said fundamental frequency.

6. A magnetron discharge tube and circuit therefor, said tube having a central linear cathode and a plurality of cylindrically segmented anodes, said circuit comprising resonant loops at least one of which interconnects a pair of anodes, and at least one other of which loops constitutes a connection from the middle point of a first said loop to another of said anodes, the resonant loops of the class first mentioned being tuned to a frequency harmonically related to the resonant frequency of the entire circuit arrangemen-t.

'7. A magnetron discharge tube and circuit therefor, said tube having a central linear cathode and a plurality of cylindrically segmented anodes, there being an unequal number of anodes on the two sides of a bisecting plane in which said cathode lies, a resonant loop interconnecting a pair of adjacent anodes, on one side of said plane, and a resonant circuit connecting the anodes on one side of said plane with the anodes on the opposite side thereof.

8. A device in accordance with claim '7 and having means for simultaneously developing two different frequencies each harmonically related to a third or basic frequency at which said magnetron discharge tube tends to oscillate. I

9. A frequency changer comprising a magnetron discharge tube having a linear cathode lying in a plane which bisects the tube structure, and an unequal number of cylindrically segmented anodes on the two sides of said plane, a resonant loop system interconnecting the anodes on one side of said plane, and a second resonant loop system forming an interconnection between all the anodes on one side of said plane and the anode system on the other side of said plane.

10. A frequency changer according to claim 9 in which the second said resonant loop system includes the loop first mentioned and also a conductor connecting the mid-point of one such loop with a point symmetrically disposed in respect to the anode system on the other side of said bisecting plane.

11. A frequency changer comprising a magnetron discharge tube having a linear cathode and an even number of at least four cylindrically segmented anodes surrounding said cathode, each pair of diametrically opposite anodes being interconnected by a resonant circuit tuned to a given frequency, and the mid-points of said resonant circuits being interconnected by a conductor having distributed inductance and capacitance, said conductor in combination with the first said resonant circuits constituting means for developing oscillations of at least two frequencies which are harmonically related.

12. A magnetron discharge tube and circuit therefor, said tube having a central linear cathode and a plurality of cylindrically segmented anodes, said anodes being arranged in pairs of equally large and mutually opposing segments, a plurality of resonant loops each interconnecting the anodes of an appropriate pair and at least one other resonant loop which symmetrically interconnects the first said loops, the last said loop being tuned to a frequency harmonically related to a basic frequency at which said discharge tube tends to oscillate.

13. A magnetron discharge tube and circuit therefor, said tube having a central linear cathode and a plurality of cylindrically segmented anodes, said anodes comprising a single segment disposed on one side of a bisecting plane in which said linear cathode lies, and a plurality of anode segments being n in number and equal to each other in size disposed on the opposite side of said bisecting plane, said circuit comprising a resonant loop system interconnecting adjacent anode segments which lie on said opposite side of the bisecting plane, said loop system being tuned to the nth harmonic of a basic frequency at which said discharge tube tends to oscillate, and an additional loop system symmetrically interconheating the first said loop system with the anode segment which lies singularly on the first mentioned side of said bisecting plane.

GERRIT DE VRIES. CARL G. A. VON LINDERN. 

